I've been playing with Co2 since I bought my A5, Feb 08. I've noticed sporadic accuracy at best. I borrowed a buddy of mines HPA tank and tried it out. I'd have to say the HPA shot more consistant and the weight was slightly lighter. We have a PB shop near by that charges $1 per fill air or Co2, so fill up cost is not an issue. My friends however tend to run out of air faster than my Co2 when we play at our local field, so that is a concern. I read a lot about the Palmer Stabilizers and fought about which direction I wanted to go. I decided to get a Palmer Female Stabilizer and try it out. I figure if I want to turn over to HPA in the future, I'll have dual Regs. I live in So. California where the weather is usually nice, so I don't have to deal with extreme conditions. I'm hoping I've made the right choice.